3D Carver Makes Magnetic Fields Visible

The history of science is full of examples when a 3D physical model led to a big discovery. But modelling something that’s actually invisible can be tough. Take magnetic fields – iron filings on a card will give you a 2D model, but a 3D visualization of the field would be much more revealing. For that job, this magnetic field following 3D carving machine is just the thing.

What started out as a rapid prototyping session with servos and hot glue ended up as quick and dirty 3D carving rig for [Frits Lyneborg]. The video shows his thought progression and details how he went from hot glue and sticks to LEGO Technics parts and eventually onto Makerbeam extrusions for the frame of his carver. A probe with a Hall effect sensor is coupled to a motor spinning a bit that cuts into a block of floral foam. A microcontroller keeps the Hall sensor a more or less fixed distance from a rare-earth magnet, resulting in a 3D model of the magnetic field in the foam, as well as a mess of foam nubbles. Despite a few artifacts due to in-flight adjustments of the rig, the field presents clearly in the block as two large lobes.

Carving foam isn’t the only way to visualize a magnetic field in three dimensions, of course. If you’d rather have a light show based on the local magnetic field, try this 3D compass build we covered a while back.

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Copying objects in 3D


[Pulse 9] sent in a very interesting project he just finished up at an internship. It’s a 3D photocopier that scans an object and then mills said object into floral foam.

The copier is made out of material [Pulse] found sitting around – PVC, drawer slides for the X and Y axes, acrylic for the structure, and broken printer parts for the Z axis.

To scan an object, [Pulse] puts an object down on the bed and scans it with a laser and webcam. The images recorded on the camera are fed into MATLAB. The output from MATLAB is sent over serial to a custom board containing a PIC18F4620 that controls the axis motors. The spindle for this floral foam router is a simple drill; one layer at a time, the drill mills out the unneeded foam which can be sucked up by a vacuum when the object is complete.

Below you’ll find [Pulse]’s demo of his photocopier and a piece the local news did on the project. If anyone is willing to translate that story, feel free to do so in the comments.

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LEGO mill produces sculpted models with fantastic resolution

[Arthur Sacek] has really got something with the 3D Mill he built entirely from LEGO pieces. As you can see, it uses NXT parts to control the cutter head along three axes. The drill bit that acts as the mill’s cutting head is not a LEGO part, but that’s [Arthur’s] only transgression.

The demo sculpture seen above was cut into a block of floral foam. The model was processed by Autodesk Softimage before being fed into the mill, where it took about two and half hours to complete the job. The foam comes out still in block form looking like a piece of outdoor carpeting. That’s because there’s no debris removal during the milling process. But hit it with the shopvac and you’ll reveal a physical model with surprising detail. We don’t think it comes close to the light-cured resin printing we’ve seen, but it would be a great asset if you’re doing some mold making.

Don’t miss [Arthur’s] video of the milling process after the break.

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